Added Weekly Period + Monthly Periods

[michtio]

Monthly Loop

• Added The ability to loop monthly through a given start and end date
• Takes the end of month into consideration
• Takes into consideration not all months have 31 days when that's the starting date
• Takes February into consideration when looping through the 29th/30th/31st of a month
• Takes leap years into consideration
• Possibility to use "Timestring values" e.g. Last Monday of the month

Weekly Loop

• Added the ability to loop weekly through a given start and end date
• Function can run weekly, or weekdays can be selected e.g. Every Monday, Thursday, Sunday of the week
• Sanitizing data
• Adding Timezone Functionality
• Adding DST Functionality